(a) Field of the Invention
This invention generally relates to a system for the subcutaneous delivery of medicaments, and more particularly to a hand held actuator, and a plunger and ampule or vial used to deliver a stream of medication.
(b) Discussion of Known Art
The need for a needle-less injection device that can be used to deliver a fine, high-pressure stream of medication through the skin has been recognized for some time. However, the problems associated with creating this high-pressure stream, particularly with a self-contained, hand-held device, has proven to be a greater challenge than expected. The typical approach at creating these streams has been to use a piston that is driven by a CO2 cartridge, compressed air, or a spring. The piston is then used to drive the medicament from a reservoir through a small nozzle that is used to create the fine stream that is to penetrate the skin. The size and energy of the stream allows the stream to penetrate the skin to a depth where it can then be absorbed by the body.
One important problem is the creation of such a stream is the creation of a nozzle that provides a tight, uniform stream, and not a spray of the embodiment.
Another important problem associated with the design of a needle-less injection system involves the efficient delivery of the dose of medicament held within the reservoir. In other words, it is important that the system does not allow medicament to escape between the piston and the reservoir or cylinder through which the medicament is being delivered. The problem of loss of the medicament is typically caused by the escape of medicament under the pressure required to adequately deliver the medicament through the nozzle.
Still another important problem associated with needle-less injection devices, and particularly with hand-held devices of this type, is the provision of sufficient power to create and deliver a stream with sufficient energy so that the stream can penetrate the body to a depth where the medicament can be absorbed.
Yet another problem associated with needle-less devices is maintenance of a required amount of pressure during the delivery of the medicament from the reservoir, through the nozzle.